Why do i look sad, while doing things consciously?

I think being conscious and mindful must make you look sad. Quite the contrary. If you look sad, you might just have attached to much to what you're doing, feeling tense and tightened up. This may become obvious if you feel the tension in your forehead and tell yourself to relax.

There's a strong coupling between the expressions of the body and the feelings. If you are experiencing joy in any form, it's almost impossible to look sad.

As in meditation, when that little sparkle of bliss comes up, there's no reason not to look happy.

Allow yourself to enjoy the work you're doing, smiling and laughing isn't a bad thing. Maybe you find reasons for happiness within the work, as you are content with well it all fits together. There's no obligation to freak out about some superficial video on the internet - there are so many real nice things your mindfulness can observe.

I don't want to laugh anymore

Why? What happened? Why can't you laugh in a situation meditatively?

I myself was like this. Not talking. Being silent. Not involved in/Aloof from the situation.

I think you are misunderstanding the meditative nature a little bit. When you are playing a game, why won't you be joyful or laugh? Or be disappointed if you lose. And still feel that everything is okay.

See, Lord Buddha said, as quoted, I am awake. Which means he would laugh when the situation is so, shed tears when the situation is so, advise people when situation is so.

It seems like you are getting stuck and taking life too seriously. See you can be serious when required and joyful when required. What is the problem?

Buddhism deals with the mind. "Are you sad?" Or "are you sad not?" These are distractions. Distractions keeps one from progressing - one hears others louder than the practice.

I have started doing things consciously, i don't want to laugh anymore, i just want to maintain that inner peace felt in doing things meditatively. But people have started asking that "i am looking sad". Should i smile or should i go with the flow, i want to follow Lord Buddha.

This is a similar experience i've encountered.When I do things meditatively i usually look like i'm in a trance like state.My eyes are down cast.I don't talk a lot.I keep to myself.I have also observed, i also look quite expressionless.This can sometimes be misconstrued as sad.But i feel enormousness peace.I'm just not animated.

In our society today, everyone has to be constantly talking,reacting,bubbly,hyped,on their phones,smiling,being a running commentary on daily events..Two people have expressed concern about me because i don't seem as interested in many things,since they equate happiness with "doing" things.Travelling,partying,listening to music,adventure,talking about anything under the sun etc.(Accumulating more experiences).

After experiencing peace from meditation my idea of happiness is more of peace and stillness.Instead of smiling,looking happy and experiencing more experiences.

I think you have some ideas collapsed.

I don't want to laugh anymore

If this is actually a goal, I'd like to suggest that you may have wandered off from your true intention.

Mindfulness during daily activity can produce a sense of peace and satisfaction, but if it is so self-contained that it forbids laughter, it becomes restrictive, and won't produce anything lasting.

While concentration is important, mindfulness includes the entirety of your environment, not just the task at hand. That means mindfulness includes attentiveness to others; to the dog across the street wagging his tail in such a way that you can't help but laugh; to the non-restrictive space that grants being to all that exists.

A couple quotes:

If you wish to understand yourself, you must succeed in doing so in the midst of all kinds of confusions and upsets. Don’t make the mistake of sitting dead in the cold ashes of a withered tree. - Enyo

and

[Mindfulness] is doing each thing you do as if it is your one and only chance for self-expression, joy, freedom, and peace of mind. - Werner Erhard

Don't get attached to the peace of mind part. Mindfulness that is overly self-conscious will leave you attached to being 'good at concentrating' or something. Open yourself to your task and the environment within which the task exists - let the outward expression of joy you find in your practice be a gift to those who are near.